The behaviour of footings resting on a non-homogeneous soil mass with a crust. Part II. Circular footings

1981 ◽  
Vol 18 (2) ◽  
pp. 265-279 ◽  
Author(s):  
R. K. Rowe ◽  
J. R. Booker
Keyword(s):  
Soil Mass ◽  
Soil Parameters ◽  
Layer Depth ◽  
Worked Example ◽  
Wide Range ◽  
Homogeneous Soil ◽  
Cross Anisotropy ◽  
Strip Footings ◽  
Underlying Soil ◽  
Elastic Soil

The behaviour of circular footings resting on a non-homogeneous elastic soil with a crust is investigated. The stiffness of the crust is assumed to be either constant or to decrease with depth, whereas the stiffness of the underlying soil increases linearly with depth.Consideration is given to the effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil upon the settlement profile. The behaviour of circular footings is then compared with that of strip footings and the relative importance of the crust and the underlying soil parameters is discussed.The influence of cross-anisotropy upon footing response is briefly examined and the effects of neglecting anisotropy are indicated for a number of soil profiles.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of circular footings for a wide range of practical cases. The use of these charts is illustrated by means of a worked example.

The behaviour of footings resting on a non-homogeneous soil mass with a crust. Part I. Strip footings

1981 ◽  
Vol 18 (2) ◽  
pp. 250-264 ◽  
Author(s):  
R. K. Rowe ◽  
J. R. Booker
Keyword(s):  
Soil Mass ◽  
Elastic Response ◽  
Soil Parameters ◽  
Wide Range ◽  
Weathered Crust ◽  
Homogeneous Soil ◽  
Finite Layer ◽  
Strip Footings ◽  
Underlying Soil

A convenient and economical finite layer method of analysing the behaviour of footings on a non-homogeneous soil is outlined. This method of analysis is used to investigate the elastic response of strip footings for a wide range of soil profiles involving a weathered crust overlying a main deposit. The stiffness of the crust is considered to be either constant or to decrease with depth while the stiffness of the underlying deposit increases with depth.The effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil are examined. The influence of this non-homogeneity upon settlement profile, differential settlement, and consolidation settlement are discussed and the results obtained from this detailed analysis are compared with results obtained from the approximate use of existing homogeneous elastic solutions.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of footings for a wide range of practical cases. The applicability of the solutions and the determination of soil parameters is briefly discussed.

Two-pile interaction factor revisited

2011 ◽  
Vol 48 (5) ◽  
pp. 754-766 ◽  
Author(s):  
S.L. Chen ◽  
C.Y. Song ◽  
L.Z. Chen
Keyword(s):  
Axial Strain ◽  
Pile Group ◽  
Soil Mass ◽  
Soil Parameters ◽  
Pile Head ◽  
Soil System ◽  
Axial Forces ◽  
Interaction Factor ◽  
Wide Range ◽  
Pile Interaction

A rigorous analytical method is developed for calculating the interaction factor between two identical piles subjected to vertical loads. Following the scheme proposed by Muki and Sternberg, the problem is formulated by decomposing the pile soil system into an extended soil mass and two fictitious piles. With the consideration of the compatibility condition that the axial strain of the fictitious pile be equal to the corresponding strain average over the extended soil, a Fredholm integral equation of the second kind governing the unknown axial forces along fictitious piles is established and then solved using numerical procedures. The real pile head settlement is subsequently calculated based on the determined fictitious pile forces and finally, the desired pile interaction factor is derived. Comparison with existing solutions confirms that the conventional interaction factor approach does tend to overestimate the interaction and may cause considerable errors for long compressible piles. Numerical results for the interaction factor between two piles in both semi-infinite and finite layered soils are presented over a wide range of pile and soil parameters, and also the settlement behaviour of a 3 × 3 pile group embedded in a semi-infinite soil is studied by virtue of the newly established interaction factor.

scholarly journals Sea-surface CO<sub>2</sub> fugacity in the subpolar North Atlantic

2008 ◽  
Vol 5 (2) ◽  
pp. 535-547 ◽  
Author(s):  
A. Olsen ◽  
K. R. Brown ◽  
M. Chierici ◽  
T. Johannessen ◽  
C. Neill
Keyword(s):  
North Atlantic ◽  
Surface Waters ◽  
Mixed Layer Depth ◽  
Sea Surface ◽  
First Year ◽  
Layer Depth ◽  
High Resolution Data ◽  
Chl A ◽  
Wide Range ◽  
Summer Warming

Abstract. We present the first year-long subpolar trans-Atlantic set of surface seawater CO2 fugacity (fCO2sw) data. The data were obtained aboard the MV Nuka Arctica in 2005 and provide a quasi-continuous picture of the fCO2sw variability between Denmark and Greenland. Complementary real-time high-resolution data of surface chlorophyll-a (chl-a) concentrations and mixed layer depth (MLD) estimates have been collocated with the fCO2sw data. Off-shelf fCO2sw data exhibit a pronounced seasonal cycle. In winter, surface waters are saturated to slightly supersaturated over a wide range of temperatures. Through spring and summer, fCO2sw decreases by approximately 60 μatm, due to biological carbon consumption, which is not fully counteracted by the fCO2sw increase due to summer warming. The changes are synchronous with changes in chl-a concentrations and MLD, both of which are exponentially correlated with fCO2sw in off-shelf regions.

scholarly journals Analysis of beam-column elements on non-homogeneous soil using the differential transformation method

2021 ◽  
Author(s):  
Juan Sebastián Carvajal-Muñoz ◽  
Carlos Alberto Vega-Posada ◽  
Julio César Saldarriaga-Molina
Keyword(s):  
Boundary Conditions ◽  
Elastic Foundation ◽  
Mathematical Formulation ◽  
Transformation Method ◽  
Transverse Load ◽  
Differential Transformation Method ◽  
Differential Transformation ◽  
Pasternak Elastic Foundation ◽  
Wide Range ◽  
Homogeneous Soil

This paper describes an analytical approach to conduct an analysis of beam-column elements with generalized end-boundary conditions on a homogeneous or non-homogeneous Pasternak elastic foundation. The mathematical formulation utilized herein is that presented by the senior author in a recent work. The differential equation (DE) governing the behavior of the beam-column element is solved using the differential transformation method (DTM). The DTM offers practical advantages over other conventional approaches when solving the proposed structural model. The proposed formulation provides the flexibility to account for i) combined lateral and axial load at the ends of the element, ii) homogeneous or non-homogeneous soil, iii) Pasternak elastic foundation, and iv) an external arbitrary transverse load acting on the element. The effects of various slenderness ratios, pile-soil stiffness ratios, and classical and semirigid boundary conditions can be easily studied with the proposed formulation. Examples are presented to validate the accuracy of the model and its applicability over a wide range of analyses.

scholarly journals An evidence- and risk-based approach to a harmonized laboratory alert list in Australia and New Zealand

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Craig A. Campbell ◽  
Que Lam ◽  
Andrea R. Horvath
Keyword(s):  
New Zealand ◽  
High Risk ◽  
Significant Risk ◽  
Working Party ◽  
Worked Example ◽  
Decision Points ◽  
Risk Result ◽  
Wide Range ◽  
Assessing Method ◽  
Alert Threshold

Abstract Individual laboratories are required to compose an alert list for identifying critical and significant risk results. The high-risk result working party of the Royal College of Pathologists of Australasia (RCPA) and the Australasian Association of Clinical Biochemists (AACB) has developed a risk-based approach for a harmonized alert list for laboratories throughout Australia and New Zealand. The six-step process for alert threshold identification and assessment involves reviewing the literature, rating the available evidence, performing a risk analysis, assessing method transferability, considering workload implications and seeking endorsement from stakeholders. To demonstrate this approach, a worked example for deciding the upper alert threshold for potassium is described. The findings of the worked example are for infants aged 0–6 months, a recommended upper potassium alert threshold of >7.0 mmol/L in serum and >6.5 mmol/L in plasma, and for individuals older than 6 months, a threshold of >6.2 mmol/L in both serum and plasma. Limitations in defining alert thresholds include the lack of well-designed studies that measure the relationship between high-risk results and patient outcomes or the benefits of treatment to prevent harm, and the existence of a wide range of clinical practice guidelines with conflicting decision points at which treatment is required. The risk-based approach described presents a transparent, evidence- and consensus-based methodology that can be used by any laboratory when designing an alert list for local use. The RCPA-AACB harmonized alert list serves as a starter set for further local adaptation or adoption after consultation with clinical users.

Some investigations into soil and vegetation relationships associated with alkaline-saline soil surfaces in the Walcha area, Northern Tablelands, New South Wales

1995 ◽  
Vol 46 (1) ◽  
pp. 209 ◽  
Author(s):  
KH Kreeb ◽  
RDB Whalley ◽  
JL Charley
Keyword(s):  
Cynodon Dactylon ◽  
New South ◽  
New South Wales ◽  
Soil Surface ◽  
Tree Planting ◽  
Soil Parameters ◽  
Alkali Cations ◽  
Grazing Land ◽  
South Wales ◽  
Wide Range

The characteristics of the soil, vegetation and groundwater at a dryland salinity site on Miramoona, a property near Walcha on the Northern Tablelands of New South Wales, were investigated. Soil parameters measured at 23 points along a 200 m transect were highly correlated with the pattern of vegetation. Of overriding significance was soil pH, which varied from a high of over 10 on bare areas delineated by Critesion marinum and Cynodon dactylon to a low of less than 5 on grazing land supporting the growth of a wide range of pasture species. The bare areas were characterized by alkalinity. While they were sodic at all depths measured, they were only marginally saline and then only at the soil surface. The chemical composition of the groundwater collected from three piezometer tubes varied quite markedly over the site. It is hypothesized that the presence of alkaline bare areas on the Northern Tablelands is not a new problem, but rather the natural result of alternating wet and dry periods which have induced accumulation of carbonates and bicarbonates of the alkali cations, notably sodium. Drainage of the original perched swamps by the early landholders, tree clearing and the grazing of domestic livestock would have accelerated the process since European settlement. However, tree planting would appear unlikely to have any impact on the reclamation process in the short term. A more viable option would be the recreation of the original swamps in suitable situations, although this solution would create problems for grazing management.

Soil Cohesion Development under Different Pore and Size Characteristics

2020 ◽  
Author(s):  
Cagla Temiz ◽  
Fikret Ari ◽  
Selen Deviren Saygin ◽  
Sefika Arslan ◽  
Mehmet Altay Unal ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Soil Properties ◽  
Size Distribution ◽  
Fluidized Bed ◽  
Soil Mass ◽  
General Terms ◽  
Soil Cohesion ◽  
Wide Range ◽  
Fluid Bed

&lt;p&gt;Soil cohesion (Co) is one of the most important physical soil characteristics and it is closely related to the basic soil properties and physical distribution forces (e.g. particle size distribution, pore sizes, shear strength) and so it is mostly determined by experimentally approaches with the help of other soil properties in general terms. Instead of using these assumptions, the fluidized bed approach provides an opportunity for direct measurement of intrinsic soil cohesion. In this study, soil cohesion development for different soil types was investigated with the fluid-bed method by which pressure drop in soil mass measures under increasing water pressures until the cohesion between particles disappears. For this purpose, 20 different soils varying with a wide range of relevant soil physical properties were sampled; such that clay, silt and sand contents varied between 2% and 56%, 1% and 50%, and 1% and 97%, respectively while porosity values were between 0.38 and 0.92. By those textural diversities of the soils, obtained cohesion values changed between 5203 N m&lt;sup&gt;-3&lt;/sup&gt; and 212276 N m&lt;sup&gt;-3&lt;/sup&gt;. Given results from regression analysis, a significant relationship was found between cohesion values of the soils and their porosity and silt fractions (R&lt;sup&gt;2&lt;/sup&gt;: 86.6).These findings confirm that the method has a high potential to reflect differential conditions and show that soil cohesion could be modeled by such basic and easily obtainable parameters as particle size distribution and porosity, as well.&lt;strong&gt;&amp;#160;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Key words&lt;/strong&gt;; &lt;strong&gt;Mechanical soil cohesion, particle size distribution, fluidized bed approach, porosity&lt;/strong&gt;&lt;/p&gt;

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